Ice bank heat exchanger

ABSTRACT

An ice bank heat exchanger including a process water retaining reservoir provided with a hot process water inlet and a water outlet returning cooled water to the process equipment, a refrigeration unit associated with the said reservoir and expanding through evaporator coils contained within the said water reservoir, the evaporator coils being affixed to ice bank plates which are arranged within the reservoir to freeze the stored process cooling water and to provide a serpentine water path therethrough from the hot water inlet connection to the cooled water outlet connection.

United States Patent Bernstein June 27, 1972 [54] ICE BANK HEATEXCHANGER [72] Inventor: Arthur Bernstein, 2636 North Hutchinson Street,Philadelphia, Pa. 19133 [22] Filed: Jan. 21, 1970 [21 1 Appl. No.: 8,101

[52] US. Cl ..62/ 139, 62/59, 62/436 [51] Int. Cl ..F25d 17/02 [58]Field of Search ..62/59, 436, 139, 272, 430, 62/435, 431; 165/146 [56]References Cited UNITED STATES PATENTS 2,448,453 8/1948 Morrison ..62/59X 2,538,015 1/1951 Kleist ..62/59 X 2,853,859 9/1958 Thompson ..62/272Primary Examiner-William L. Wayner Attorney-Karl L. Spivak [5 7]ABSTRACT An ice bank heat exchanger including a process water retainingreservoir provided with a hot process water inlet and a water outletreturning cooled water to the process equipment, a refrigeration unitassociated with the said reservoir and expanding through evaporatorcoils contained within the said water reservoir, the evaporator coilsbeing affixed to ice bank plates which are arranged within the reservoirto freeze the stored process cooling water and to provide a serpentinewater path therethrough from the hot water inlet connection to thecooled water outlet connection.

1 Claim, 4 Drawing Figures PATENIEDJunm I972 INVENTOR.

ARTHUR BERNSTEIN ATTOR NEY.

rcr: BANKHEAT EXCHANGER BACKGROUND OF THE INVENTION The presentinvention relates to an ice bank type of heat exchanger suitable forreducing the temperature of heated process cooling water economicallyand in an extremely confined area.

In various industrial processes such as dry cleaning, it is necessary toreclaim the solvents or other materials being employed in the equipmentsuch as perchlorethylene or trichlorethylene to thereby facilitateeconomical process utilization. In-the past, it has been customary toreclaim solvents and other'materials by means of coils of copper tubingpositioned within the equipment to permit relatively cool city water toflow therethrough to cool the heated solvents. Perchlorethylene'andtrichlorethylene are particularly suited for theservice inasmuch as theyare non-flammable and have the property -to condense sufficientlyforreuse from the vaporized state after utilizationfor cleaning purposes tothe liquid state at temperatures below 90 F. Accordingly, normallyavailable city water has usually proved satisfactory for solventcondensing without further cooling. On occasion, however, duringextended not weather periods, the ground water has reached temperaturesthat were sufiiciently elevated as to seriously interfere with thecooling process. Such temperatures resulted in great loss in efficiency.Also, it was the usual practice to waste all water used for solventcooling purposes, thereby providing a system that was furtherunsatisfactory both from a standpoint of operating economy and also froma standpoint of water conservation.

Normal water reclaiming machinery such as cooling towers and evaporativecondensers have been employed by prior workers in the field in anattempt to solve the difiiculties above mentioned. However, it was foundthat these devices were not suitable for use in many dry cleaningestablishments for several reasons. Cooling towers are quite bulky insize and require largevolumes of air. It has usually been found that thenecessary space and air requirements for his type of equipment is notreadily available, especially in heavily populated metropolitan area.Additionally, such water cooling equipment must operate throughout theyear and accordingly, considerable winterizingcdsts were encountered byprior workers in those areas subject to freezing temperatures. Suchunits also provided problems in the summer time in locations subject toexcessive heat wherein high wet bulb temperatures would be approachingthe top permissible solvent condensing temperatures. Evaporativecondensers, when they were employed, incorporated most of the samedesign problems as encountered with cooling towers with the additionthat such equipment greatly increased the initial installation costs.

It has thus become necessary to design a piece of equipment that iscapable of eliminating consumption and waste of water and at the sametime is capable of producing relatively cool water to increase theefficiency of the solvent reclaiming process. As a design criterion, theequipment must be compact enough to be installed in the work area ofcrowded plants and must further be capable of operating at high ambienttemperatures in the work area under all outside conditions of climateand humidity.

Prior workers in the art have heretofore been unable to design atrouble-free, economical and efficient water cooling unit of a sizecompact enough to fitwithin the space available in crowded plantsrequiring the use of process cooling water.

SUMMARY OF THE INVENTION Accordingly, the present invention relates to arelatively compact ice bank heat exchanger of the closed circuit typesuitable for water cooling purposes under all ambient conditions oftemperature and humidity.

In order to conserve space, the present invention includes an insulatedreservoir of water which incorporates a refrigerated ice bank capable offreezing a quantity of ice in the retained water. Inlet and outlet waterconnections communicate the liquid to be cooled with the interior of.the water reservoir and a gasketed cover prevents evaporation of thecooling water. Inasmuch as the hear of fusion of ice is 144 BTU/lbfE, incontrast to the heat of water above freezing which gives up only oneBTU/lbfE, the storage value of such a refrigerated ice bank reservoir istherefore 144 times as great as that of a given weight of water.Accordingly, an extremely small, efficient water reservoir can thus beemployed to achieve the cooling effect of a much larger water type heatexchanger. Additionally, since the process utilizing the vapors beingcondensed is not nonnally operated over a 24 hour day period and 7 daysa week, the periods of plant down time can be employed for manufacturingice for utilization during the operating period, thus economicallypermitting the installation of a smaller compressor and motor.

Ice making plates have been provided within the interior of the waterreservoir and the plates are soarranged as to cause the heated processcooling water flowing through the unit to follow an elongated serpentinepath betweenthe water inlet and water outlet to thereby prolong contactbetween the cooling water and the ice to assure adequate cooling.Additionally, because the water delivered from the process equipment tothe reservoir inlet is generally warm from the nature of the process,ice at the plates nearest the water inlet melts first to cool the water.As the temperature of the cooling water declines because of the coolingeflect of the ice, ice on the remaining plates melts at a declining rateas the plates are spaced further from the water inlet, thereby leavingmore ice on the plates furthest from the inlet. Thus, when the unit goesback into the ice making cycle during the off peak hours, continuedoperation of the compressor would tend to build up more ice on thefurthest plates from the water inlet inasmuch as they would have beenunequally defrosted. Without the plate spacing compensation, a solid icebuild-up between plates could occur, thereby clogging the serpentinewater path through the unit. It is a feature of this invention to spacethe platesfurthest from the water inleta progressively increasinglydistance apart to thus prevent unequal solid ice build-up by equalizingthe equivalent cooling efiect between plates.

Anice bank control is provided near the first plate closest to the waterinlet and is spaced from the plate to thereby control the thickness ofice-build on the plate to thus furnish the refrigeration unit withacontrol responsive to the icing Conditions within the water reservoir.The uneven spacing of the plates tends to keep the freezing thickness ofice upon the plates approximately equal throughout the unit.

Accordingly, it is an object of the present invention to provide animproved ice bank heat exchanger of the type set forth.

It is another object of the present invention to provide an ice bankheat exchanger capable of economically cooling a water system.

It is another object of the present invention to provide an ice bankheat exchanger of the closed type designed to provide efi'icient watercooling facilities without loss of water through waste or evaporation.

It is another object of the present invention to provide an ice bankheat exchanger including a completely closed water cooling systemincorporating a water reservoir that is internally divided by platesinto an elongate water flow path.

It is another object of the present invention to provide an ice bankheat exchanger designed to produce an ice bank during ofi peak periodsby economically utilizing the smallest possible refrigeration system.

It is another object of the present invention to provide an ice bankheat exchanger incorporating adjustable means to regulate the build-upof ice upon interior plate construction.

It is another object of the present invention to provide an ice bankheat exchanger incorporating a water reservoir and a plurality of iceplates spaced within the reservoir, the spacing between the plates beingvaried.

It is another object of the present invention to provide an ice bankheat exchanger incorporating a water reservoir and a plurality of platesspaced within the reservoir, the spacing between the plates beingprogressively wider the more distant the plates are positioned from thewater inlet.

It is another object of the present invention to provide an ice bankheat exchanger that is rugged in construction, simple in design andeconomical when in use.

Other objects and advantages of the invention will become apparent byreferring to the following description and claims of the preferredembodiments thereof, taken in conjunction with the accompanying drawing,wherein like reference characters refer to similar parts throughout theseveral views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front perspective view ofan ice bank heat exchanger constructed in accordance with the presentinvention, partially broken away to show the internal construction.

. FIG. 2 is a cross sectional view taken along Line 2-2 of FIG. 1,looking in the directionof the arrows.

FIG. 3 is a cross sectional view taken along Line 33 of FIG. 1, lookingin the direction of the arrows.

FIG. 4 is a schematic, perspective view showing the refrigeration systemand plates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Althoughspecific terms are used in the following description for the sake ofclarity, these terms are intended to refer only to the particularstructure of my invention selected for illustration in the drawings andare not intended to define or limit the scope of the invention.

Referring now to the drawings, I show an ice bank heat exchangergenerally designated and including a generally rectangular waterreservoir 12 which is preferably interiorly fabricated of noncorrosivematerial such as stainless steel. Process cooling water inlet and outletconnections 14, 16 communicate with the interior of the reservoir atdiagonally opposed locations to facilitate the flow of process waterthorough the apparatus for optimum cooling purposes. The reservoirjacket preferably is fabricated of insulated materials to minimize heatloss through the jacket. A tight fitting, gasketed cover 18 encloses thetop of the heat exchanger to thereby provide a closed water system toreduce water loss through evaporation to a minimum.

A plurality of corrosion resisting plates 20, 22, 24, 26 verticallyposition within the reservoir 12 and affix at alternate ends of thereservoir to provide an elongate water path from the water inlet 14 tothe water outlet 16 through the unit as best seen by following the arrowpath illustrated in FIG. 3. Each plate 20, 22, 24, 26 preferably isformed of aluminum or other corrosion resistant heat conductive materialand each plate carries an amxed length of evaporator coil 28 thereonwhich preferably arranges in a serpentine pattern in wellknown manner touniformly produce ice 36 over the sides of each plate. As best seen inFIG. 4, each refrigerant coil 28 operatively connects between therefrigerant inlet manifold 30 and the suction manifold 32 to therebyunifomily develop a layer of ice 36 upon the sides of each plate.

It is the purpose of this invention to utilize the refrigerant coils 28in conjunction with the refrigerating unit 34 to build up a bank of ice36 on the plates 20, 22, 24, 26 during the evening hours when the plant(not shown) is not normally operating. In this manner, a refrigeratingunit 34 of the smallest possible size may thus be economically employedfor process water cooling purposes. The supply of ice 36 that isproduced during the evening hours is then utilized during the day forprocess water cooling purposes when the plant is normally operated.Inasmuch as ice is equivalent to 144 BTUs per pound per hour for coolingpurposes, and 1 pound of water gives up 1 BTU per pound per hour per F.,one pound of ice will .then have the equivalent cooling capacity of 144pounds of water, thus permitting economical utilization of the smallestpossible size heat exchanger.

Referring now to FIG. 4, the refrigerating unit 34 comprises acompressor 38 which receives refrigerant from the suction manifold 32.Compressed refrigerant flows from the compressor 33 to the air cooledcondenser 40 where heat is expelled to condense the refrigerant from agas to a liquid in the usual manner and the liquid refrigerant is thendirected to the refrigerant receiver 42. The stored refrigerant in thereceiver 42 flows to the inlet manifold 30 of the evaporator coils 28through a thermostatic expansion valve 44 in accordance with well-knowrefrigerating principles in response to a system control device such asthe bulb 48. The coils 28 each connect in parallel across the inletmanifold 30 to the suction manifold 32 to thereby provide uniformcooling efl'ects at each plate 20, 22, 24, 26 throughout the interior ofthe reservoir 12.

The refrigerating plates 20, 22, 24, 26 discreetly space within thereservoir to provide a serpentine path of water travel from the waterinlet 14 through to the water outlet 16 to maximize the contact of theprocess cooling water 60 with the ice 36 to assure adequate coolingduring the course of water travel through the unit 10. It should benoted that the water introduced at the inlet connection 14 is warm afterremoving heat from the plant process and accordingly, the elevated watertemperatures will melt the ice at the plates closest to the water inlet14 more rapidly when the process water is being cooled during itsserpentine path through thereservoir 12. As the process water cools uponcontact with the ice 36 which has formed on the plates 24, 26, ice onthe plates furthest from the inlet 14 will be melted at a declining ratebecause of the drop in process water temperature as it flows past theplates. More ice will thus remain on the plates furthest from the inlet14. Continued operation of the compressor 38 to rebuild the ice bank onthe plates 24, 26 closest to the water inlet 14 would tend to build anincreasing thickness of ice on the plates furthest from the water inletwhich had unequally defrosted. Such a condition could result in thebuild-up of a solid freeze of ice between the plates 20, 22 or betweenthe plate 20 and the reservoir side wall 46 to thereby interfere withnormal water passage through the heat exchanger 10. 1

Accordingly, I have found that this problem may be readily compensatedby varying the spacing between-the individual plates within the heatexchanger 10. Thus, as best seen in FIGS. 2 and 3, the plates 20, 22furthest from the water inlet 14 are spaced an increasingly greaterdistance apart both from each other and from the reservoir side wall 46.Thus, for example, should the plates 20, 22 have a tendency to build upa greater thickness of ice, the greater distance between the plate 20and the unit side wall 46 and the distance between the plates 20, 22,will permit a greater build-up of ice without completely clogging theserpentine water path through the unit from the water inlet 14 to thewater outlet 16.

An ice bank oontrol bulb 48 of conventional design to sense contact withice mounts upon the plate 26 and extends into the space 50 between theplate 26 and the reservoir side wall 47 by means of the bendablesupporting bracket 52. The ice bank control bulb 48 wires into thecompressor operating circuit at the junction box 53 to stop therefrigeration unit 34 upon sensing the build-up of a predeterminedthickness of ice 36 upon the plate 26. The thickness of the ice build-upmay be readily regulated by simply bending the bracket 52 to hold thecontrol bulb 48 either nearer or further from the plate 26.

In order to use my invention, a completely closed process water path isconstructed by conducting heated water from the process (not shown) tothe reservoir water inlet 14 by means of the inlet piping 62 andconnecting cooled water from the reservoir outlet 16 back to the processthrough the outlet piping 64 for introduction to the equipment beingcooled. If desired, a process water pump may be furnished with the icebank heat exchanger to thereby provide a completely self-containedoperating unit. The process water 60 is directed through the heatexchanger 10 wherein it follows an increasingly widening path betweenthe plates 20, 22, 24, 26 from the inlet 14 to the outlet 16. A gmketcover 18 completes the closed water system and serves to prevent loss ofwater by evaporation at the heat exchanger 10.

Process water 60 is introduced into the reservoir 12 to a controlleddepth less than the height of the evaporator coil plates 20, 22, 24, 26and the refrigeration unit 34 activates to cool the water 60. Operationof the compressor unit 38 during periods of plant inactivity when nowater flows through the reservoir 12 provides sufficient cooling at thecoils 28 to freeze the water adjacent the plates 20, 22, 24, 26 to thusbuild up a bank of ice 36 on each side of each plate. The thickness ofice may be precisely regulated by varying the distance of the icesensing bulb 48 from its associated plate 26. The bulb 48 shouldposition to control the expansion valve 44 to close before there is acomplete ice blockage between plate 26 and the reservoir side wall 47which is adjacent the water inlet 14 or between the pair of plates 20,22 most remote from the water inlet 14.

The ice sensing bulb 48 preferably positions in the space 50 whichinitially receives the heated process water from the inlet 14, thuscausing ice at the bulb 48 to melt first. In this manner, the sensingbulb functions to activate the refrigeration system 34 immediately uponinitiation of melting within the reservoir 14 to retard the rate of icedisapearance. Accordingly, the refrigeration unit 34 functions duringthe off peak hours to build up an ice bank for water cooling purposesand further functions during the plant operating periods to retard theice melting rate by tending to freeze additional quantities of ice.

It should be noted that the process water 60 itself is utilized tofreeze to form the ice bank 36. When the ice 36 is melted by the warmedprocess water, the water from the melt mixes with the process water andis recirculated therewith. Thus the same water supply serves the dualpurpose of cooling the process equipment and also of supplying thenecessary water for the build-up of the ice bank.

I claim: I

1. In an ice bank heat exchanger suitable for cooling previously heatedwater of the type including a refrigeration system to build up a supplyof ice within the unit on plates positioned therewithin, the combinationof A. a water storage reservoir receiving the said heated water andincluding a bottom and a pair of spaced sides and a pair of spaced endswhich define an interior space,

1. said reservoir being provided at one end thereof with a heated waterinlet and at the other end thereof with a cooled water outlet;

B. a plurality of evaporator plates positioned within the interior spaceand extending vertically from the said bottom, 1. said platespositioning in vertical planes parallel with the reservoir sides,

2. said plates forming substantially water tight connections with thereservoir bottom,

3. each plate being generally rectangular in shape and having aconnected edge and a free edge,

a. the said connected and free edges defining a lateral distance lessthan the distance between the ends of the reservoir,

b. the connected edge of each plate affixing to one end of the reservoirin a substantially water tight connection,

c. the said plate connected edges being staggered alternately from endto end of the reservoir to form a serpentine water path through thereservoir from the water inlet to the water outlet,

4. the horizontal spacing between adjacent plates increasing as theplates position further from the said water inlet; and

C. a refrigerant system control associated with the first platepositioned closest to the water inlet,

1. said control stopping the refrigeration system upon the build-up of apredetermined thickness of ice upon the said first plate.

l l 1 i

1. In an ice bank heat exchanger suitable for cooling previously heatedwater of the type including a refrigeration system to build up a supplyof ice within the unit on plates positioned therewithin, the combinationoF A. a water storage reservoir receiving the said heated water andincluding a bottom and a pair of spaced sides and a pair of spaced endswhich define an interior space,
 1. said reservoir being provided at oneend thereof with a heated water inlet and at the other end thereof witha cooled water outlet; B. a plurality of evaporator plates positionedwithin the interior space and extending vertically from the saidbottom,
 1. said plates positioning in vertical planes parallel with thereservoir sides,
 2. said plates forming substantially water tightconnections with the reservoir bottom,
 3. each plate being generallyrectangular in shape and having a connected edge and a free edge, a. thesaid connected and free edges defining a lateral distance less than thedistance between the ends of the reservoir, b. the connected edge ofeach plate affixing to one end of the reservoir in a substantially watertight connection, c. the said plate connected edges being staggeredalternately from end to end of the reservoir to form a serpentine waterpath through the reservoir from the water inlet to the water outlet, 4.the horizontal spacing between adjacent plates increasing as the platesposition further from the said water inlet; and C. a refrigerant systemcontrol associated with the first plate positioned closest to the waterinlet,
 1. said control stopping the refrigeration system upon thebuild-up of a predetermined thickness of ice upon the said first plate.2. said plates forming substantially water tight connections with thereservoir bottom,
 3. each plate being generally rectangular in shape andhaving a connected edge and a free edge, a. the said connected and freeedges defining a lateral distance less than the distance between theends of the reservoir, b. the connected edge of each plate affixing toone end of the reservoir in a substantially water tight connection, c.the said plate connected edges being staggered alternately from end toend of the reservoir to form a serpentine water path through thereservoir from the water inlet to the water outlet,
 4. the horizontalspacing between adjacent plates increasing as the plates positionfurther from the said water inlet; and C. a refrigerant system controlassociated with the first plate positioned closest to the water inlet,